U.S. Pat. No. 2,648,878 relates to a fully reversible hopper window. Such window has two arms that support the window and bottom guides in which it slides. However, the position of the arms is in the middle (50%) of the hopper window, preventing its imbalance that eases lifting it by very little effort.
U.S. Pat. No. 2,718,675, similar to the above patent, shows a reversible hopper window frame with two arms and sliding guides. However, this patent uses sliding arms that do not allow its imbalance that eases lifting it by very little effort.
U.S. Pat. No. 2,825,939 relates to assemblies for hopper windows. On this invention, the guides for hopper windows on top of the frame, thus it is a bottom open window; once opened, users get the air directly into their bodies without proper regulation. Furthermore, there is no imbalance allowing easy lifting by very little effort.
U.S. Pat. No. 3,721,044 shows a hopper window with double arms on each side which also improves the braking system. As on the above patent, the guides are on top of the frame and it has grooves therein. Furthermore, the guide system has a rotatable flange circulating on the frame groove that works as guide. It has no imbalance that eases lifting it by very little effort.
U.S. Pat. No. 3,722,142 shows a brake system for hopper windows using crossed arms. This system is very different than the above ones; it is used in open bottom hopper windows different than the one of this invention.
U.S. Pat. No. 4,102,012 relates to sliding hopper windows with upper and lower arms on each side, being also a system different to the one shown herein. As above, this system is used in open bottom hopper windows different than the one of this invention.
U.S. Pat. No. 4,783,131 relates to a locking system for cupboard doors. It has similar movements than the ones of this invention, as well as side guides for sliding on the bottom of the door.